As you want to get the details of pay scale after getting into NDA so here is the information of the same for you:

National Defense Academy is an institution where eligible candidates undergo a degree program approved by Jawaharlal Nehru University and other physical and necessary training.

Since it is a training academy, candidates who joins it, are not entitled to any salary, in fact you will need to pay certain amount of money as training fee which includes registration fee, enrollment fee, meal charges etc.

After successful completion of the training, your salary would rise to about 22K per month (K=1000) along with the allowances.